The next day, Tom feels great. While at the lake, he puts some of the serum in his tea. He starts to get a headache, then hears voices in his head. The fish are talking to him, asking him to stop injecting them with serum. They tell him to call for help by concentrating. Tom does so, and falls asleep.
When he awakes, there are two people standing near him. They introduce themselves as the Doctor and Peri. The fish tell Tom that they will help. Tom tells the Doctor and Peri about everything, including the voices. Peri is sarcastic, but the Doctor listens to Tom. The Doctor invites Peri to Tom's house for dinner, and sneaks a bit of Tom's tea into a test tube.
Peri has dinner at Tom's house and meets his wife Mary and his daughter Linda. At dinner Tom talks about his work, and that he never eats fish because he knows what he's injecting into them. When Peri leaves, the fish tell him that she will help because he showed her such good hospitality.
The Doctor examines the tea in the TARDIS. He works out a formula to block the side effects of the serum.
The next morning, the Doctor goes to the laboratory responsible for the serum. He meets with Dr Grahame Harden, who developed the serum. He tells Harden that the serum has hallucinogenic side effects. Harden becomes angry, not at the Doctor, but at his superiors who wouldn't let him test the serum before production. The Doctor shows him the problem with the formula and gives him the blocking agent.
At the lake, Peri meets Tom. She surreptitiously pours something into his tea. The Doctor arrives, and they make their farewells. When Tom drinks his tea, his headache goes away and he can no longer hear the fish.
- The Doctor notices that the TARDIS lab is a bit messy.
- The stories in Short Trips: Zodiac are inspired by the signs of the zodiac. This story's theme is Pisces.
to be added